"Controlled conditions" is the issue from my perspective given these cams are breaking out in the wild. You pretty much have to expect that one of two scenarios is playing out - that they're failing due to forces which are in-line with an axis perpendicular to the axle or, that they're failing due to lateral forces being applied off that axis. If they're failing due to forces in-line with that axis then there are problems with the design or manufacture - this I do not believe, doubly so after my informal test. But if they're failing due to off-axis lateral forces, then it's more like maldaly's comparison to being able to break biner gates so you shouldn't load them that way any more than you would laterally load a biner gate.

I'm guessing the tests done in 'controlled conditions' simply don't adequately address this issue of lateral forces. Rather than try to come up with a whole series of emulations of placements, I'd far rather see them address the question by just laterally breaking some Link Cam lobes and the unsegmented lobes from a variety of other brands and compare the results. That would answer the now generalized question - for off-axis lateral loads - are the segmented Link Cam lobes weaker, comparable, or stronger than unsegmented lobes? I'd rather extrapolate to the wild from that basic generalized test than from a series of poor specific emulations.

[ Edit: And take a close look at this photo (here I will go speculative as I'm no metalurgist) but this plausibly looks like it could be a case where an outward, off-axis lateral force tried to bend the outer flange out from under the axle end cap and that the inner flange, in tension, sheared on that angled plane in response to the sudden failure of the outside flange axle hole (or vice-versa). Speculative? Yes, but plausible - it would be interesting to see OP's metallurgical analysis of the break. ]

Dingus, yeah I made a only slightly exaggerated conjecture for the sake of getting my point across, but that did get my own curiousity up so I felt I might as well give it a whirl (I got a good deal on it). Not that much different than doing onsight FAs after nothing but a quick look - sometimes you get'em, lots of times you don't - but nothing ventured...

Now, if I can corral the right set up I'll have someone blow both that one and a comparable Metolius with a straight lateral force parallel with the axles using one of the inner cams that I didn't wail on.

[ That, and it's now permanently cold, wet and dark up here and Bill and I have piss else to do with ourselves but break shit for awhile... ]

you thought a gear company would put out onto the market a cam that you can break apart with hands and pliers, despite their years of development, despite the fact that they've been out a while now. you went on and on about it. you were so convinced that you bought one just to break it. you tried to break it with hands and pliers but failed

there's a big difference between failure within design spec's and "failure" outside them. harping on and on about their cam's inherent weakness without proof, proof that may well exist beyond design specs, that's your idea of being their great proponent?

there's a big difference between failure within design spec's and "failure" outside them. harping on and on about their cam's inherent weakness without proof, proof that may well exist beyond design specs, that's your idea of being their great proponent?

Yes, exactly. Again, if the LST cam was broken, as OP said, with no materials or manufacturing defects then what can you say besides out in the wild they are being subjected to forces beyond their design spec? That doesn't mean the design spec is inadequate - hell, the reason it took 'years of development' was honing those specs down to the bone with respect to weight and performance. And that in turn means the design spec of the delivered product has limitations in the real world. They're just not as obvious as, say the rigid stem on Forged Friends. And because those limitations are not obvious, the risk is people will continue using them inappropriately in places / ways like the LST pod or however you broke yours.

Insuring people understand the limitations of the design in the real world is the only way to keep the number of incidences like the one on LST down to a bare minimum and so keep the Link Cams in production. So yes, I'd say educating folks to the limitations of the design is exactly what being a proponent has to be about in this case. That is, unless they miraculously stop breaking in the wild (don't count on it) or it's shown conclusively any cam would break under similar circumstances so using these 'inappropriately' is no more risky a proposition than with any unsegmented cam.

The idea is that when a "traditional" cam rotates into a new orientation there are basically four lobes with four contact points. In an over simplified example, two of the contact points would remain stationary with respect to the rock and act as pivot points while the other two points would scratch along the rock through a small arc. The arc would be pretty colinear with the plane of the lobe and wouldn't provide excessive torque.

In the LC repositioning, there a 12 lobes repositioning, with 4 acting as above. The other 8 lobes describe much larger arcs and, more worrisome, the further they are from the pivot point, the arc traveled is increasingly less colinear with the plane of the lobe - meaning more torque on those lobes.

I should try to draw a better picture and post it.

Ah, I follow you now. You're trying to describe a LC that's placed far in a crack, with the smallest cams engaging with the rock, and the larger cams arcing over the rock as the cam rotates. That's what you're trying to describe, yes?

If so, what's your point? Those outer cams are floppy, they're not pushed against the rock by the axle/force of fall, but only by their springs.

GO

If they are moving into a decreasing volume position or across a non-uniform surface I would think there could be significant shearing forces on the lobes.

Yeah, could be. Would have to play with them in a crack to get a handle on that one.

hell, the reason it took 'years of development' was honing those specs down to the bone with respect to weight and performance

that is one hell of an assumption, to think the gear company that's been around for that long is oblivious of such things as performance margins

healyje wrote:

Insuring people understand the limitations of the design in the real world

if you truly cares, why don't you get some proof first? makes for a better education when you have concrete evidence

and it's entirely possible that you don't know all that went on on Left Ski Track, since you chose to ignore another possibility that many others have considered quite plausible. maybe you shouldn't lean so much on that just yet for your good gestures

hell, the reason it took 'years of development' was honing those specs down to the bone with respect to weight and performance

that is one hell of an assumption, to think the gear company that's been around for that long is oblivious of such things as performance margins

Baja, sometimes I think our minds just process differently enough so we're sometimes thinking the same thing, but vocalizing it differently in word and concept. At no time did I [mean to] imply OP is oblivious to performance margins. What I did say is that it obviously took years to come up with a workable trade-off of weight and performance which could deliver a product anyone would consider using. It would also appear to have had to wait for metal-injection-molding to finally accomplish that feat. And the bone in my 'down to the bone' verbage, would be the outer envelope of whatever OP defined as their requisite and necessary performance margins.

baja_java wrote:

healyje wrote:

Insuring people understand the limitations of the design in the real world

if you truly cares, why don't you get some proof first? makes for a better education when you have concrete evidence

Link Cams are breaking in the wild now and I'm betting in all likelyhood they will continue to do so. The only aspect of the Link Cam's design that's at all new, and therefore suspect, are those segmented cam lobe assemblies and, coincidently, they seem to be what's breaking. Putting two and two together makes me want to err on the side of the existence of a design limitation rather than wait for an elusive 'proof' I just don't see forthcoming at the moment. Better prudence than abandon from my perspective.

ok, since you're convinced now that the initial cam broke above spec's, if that's the case, doesn't that mean the gear didn't really fail to do its job? it was subjected to forces beyond its design limits. that's not the same as gear failing within their spec's. now the latter i'd consider a gear failure. but the former is not really the same. gear broke in both instances, but in the former, it's not unexpected. of course you should know the limitations of a piece of gear, but that applies regardless of brand. that simply goes without saying

this is why i don't believe what happened to my cam qualifies as a Gear Failure Report either, as you insisted. it broke, but it didn't really fail

seems like you really don't know anything about the process to verify all the facts after an incident. maybe you shouldn't demand what others should do, since you're obviously not knowledgeable. look, right now, even much of what i believe to be facts are simply that at this point, just things that i believe. just because i believe them to be facts doesn't make them actual facts, and they only become actual facts after they've been verified by OP. you keep saying i should state the facts of what happened? well, i did:

those are the only items about which there's no disputing about. the whole lot of the rest needs to be verified. for example, i know my cam is defect-free, but even that needs to be verified, and how much of what happened is indeed factual in turn depends a lot on that. do you understand yet? you know, it's one thing if you're insisting on something when you know what you're talking about. but you obviously don't. the way you yammer away even when you don't know what you're talking about, is this a consistent behavior pattern with you?

if you'd just pause and think for a moment, you would appreciate how significant FACT #2 is. can your breakage scenario make that happen, breaking a cam with the load of merely pulling down hard at the cam? well, apparently that is possible. i was surprised too, amazed. the equipment angle could no longer hold, unless there's some gross defect, leaving only a natural phenomenon where force can be greatly amplified by just the right flare angle, giving me an absolutely ridiculous force advantage. instead of yammering on and on about you needing to know what happened, if you really understood the concept, i shouldn't even have to tell you the rest, unless you believe in magic. you understand flared-induced force amplification? you "got" it? like hell you do

don't take this the wrong way, but the unamplified absurdity of you trying to tell me what i should do is just arbitrarily high

I think its cool to put one's money where one's mouth is. Healyje spent a hundred bucks give or take, to put his hand-wringing theory to test.

Bravo!

And what's more he posted the results even though they were quite contrary to his stated expectations. So he healyje has integrity as well..........

No question. As far as shaking his hand Dingus, if you do it soon, the imprint of the link cam is most likely still on it, he cranked hard.

The file has to get uploaded to my wifes Mac, as I'm out tonight, I should have that available tomorrow.

A statistician may say that the test was meaningless, as there was no corresponding numbers to indicate what forces were actually being applied. Certainly summer Healyje is stronger than winter healyje for instance, but by what percentage and what is the ultimate strength there?

I am looking into making a hydrolic testing device (I should say I'm looking into paying to have one built as my friend Andrew Trzynka has the brains and aptitude for this as I do not.

Certainly the flaring force multiplier phenomenon should be looked at further, if nothing else due to curiosity, despite the fact that it appears to rarely been seen in the wild.

Meantime while you wait for me to download the video, I think that despite all the wrangling and internet yowling, it's a good thing to gather as much information and intelligence as possible. In that vein, this added to our collective knowledge base.

if you'd just pause and think for a moment, you would appreciate how significant FACT #2 is. can your breakage scenario make that happen, breaking a cam with the load of merely pulling down hard at the cam? well, apparently that is possible. i was surprised too, amazed. the equipment angle could no longer hold, unless there's some gross defect, leaving only a natural phenomenon where force can be greatly amplified by just the right flare angle, giving me an absolutely ridiculous force advantage.

Did you repeat the same experiment with a "normal" cam, i.e. without a segmented lobe? If so, did that cam break, pull out, or stay in place?

no, i haven't. might try that, or someone else can. i don't believe people ever reached that far into that pod to place smaller sized gear, before the Link Cam. or just demonstrate the phenomenon in the lab

the question that needs to be answered, and where the real speculation lies, is whether the statement 'any make cam would have broken (versus blown) in these cases is true or not. I still do not believe that is the case and believe Link Cams are more vunerable to breakage because of the mechanical linkages. Hey, I'd love to be proven wrong, but until I am, I'm standing by my opinion mechanical linkages are inherently weaker than solid material - and hence the need to be more careful and circumspect when using them.

Yeah I agree, if your going to resort to purely mechanical means to break the lobes you should go ahead and measure the forces applied while your at it. If you and Bill actually invest the time and money into building or buying a hydrolic device and force gauge to break cams with, let me know. You can't have my Camalots but I have doubles in most Power Cam sizes and and will donate one of them and a Trango in the sizes comparable to the other lobes your testing. Hell I'll even pay shipping, just get some good video.

It seems inconceivable to me that various manufacturers have not done extensive testing in flared placements. The data has to be out there, I guess its just a matter of whether or not they have made any of it public or published it. Anybody out there have any friends within the big manufacturers?

The idea is that when a "traditional" cam rotates into a new orientation there are basically four lobes with four contact points. In an over simplified example, two of the contact points would remain stationary with respect to the rock and act as pivot points while the other two points would scratch along the rock through a small arc. The arc would be pretty colinear with the plane of the lobe and wouldn't provide excessive torque.

In the LC repositioning, there a 12 lobes repositioning, with 4 acting as above. The other 8 lobes describe much larger arcs and, more worrisome, the further they are from the pivot point, the arc traveled is increasingly less colinear with the plane of the lobe - meaning more torque on those lobes.

I should try to draw a better picture and post it.

Ah, I follow you now. You're trying to describe a LC that's placed far in a crack, with the smallest cams engaging with the rock, and the larger cams arcing over the rock as the cam rotates. That's what you're trying to describe, yes?

If so, what's your point? Those outer cams are floppy, they're not pushed against the rock by the axle/force of fall, but only by their springs.

GO

If they are moving into a decreasing volume position or across a non-uniform surface I would think there could be significant shearing forces on the lobes.

Yeah, could be. Would have to play with them in a crack to get a handle on that one.

GO

Here's the poor pictures that demonstrate crudely how the re-orienting of the LCs in fully extended form is a very different operation from a traditional three- or four-lobed cam.

The LC (three sets of lobes shown independently) has its smaller (extended) lobes traveling much further relatively, and in a direction more perpendicular to the plane of the lobe. I can see how if you have this stuffed into a flaring pocket you could really generate some weird torques.

Sorry that the scales are different in the pictures and the LC doesn't look like a real LC.

no, i haven't. might try that, or someone else can. i don't believe people ever reached that far into that pod to place smaller sized gear, before the Link Cam. or just demonstrate the phenomenon in the lab

To me, that would be the most interesting thing to come out of this discussion, what are the practical differences in performance between a link cam and standard cams that we are all more familiar with. Helps to understand the limitiations or potential performance differences, or possibly the lack there of.

Sounds like this pod offers a somewhat unique opportunity to observe this, as it sounds like failure can be obtained with relatively low force applied to the cam.

Heard from Omega Pacific today that the Link Cam I'd fractured was "without defect," that "everything was within spec." OP is presently looking into the flare-induced force amplification possibility. They might say something soon, or at a later time. They plan to come down to Joshua Tree to have a good look at that flared pod on Left Ski Track, and possibly make a model of it to take back and study in detail.

This Red #1 Link Cam was fractured while I was on Left Ski Track the second time, back on Jan 1st. I hadn't noticed the fracture immediately on the spot because I wasn't looking to break the cam. I was only up there to check out the other placement options, and how the cam behaved when one set of lobes pulled free. So I wasn't checking for fractures before and after each placement and pull. As the photos show, the small partial fracture was on only the inside connection flange, with no damage on the outside flange, and was not easily noticeable at a glance while out on the rock. I found the fracture two days after I've returned home, when I was again examining and playing with the cam. I immediately contacted OP and sent the cam to them at WA. The discovery of the fracture not being on the scene, I felt it important to sort out the facts with OP first. Hope that's understandable.

The fracture resembled that of Dirtme's cam very much. His occurred on a short lead fall. Mine happened as a result of only downward pulls by hand. The force of the pulls were about that of setting a piece hard, but not as hard as all out funking. Sorry I couldn't be more precise, or for not measuring the force of the pulls. Again, I wasn't out there to break cams.

I'm very sure there wasn't any fracture prior to the second outing, given how much I'd played with that cam, on and off again, looking especially at that same spot corresponding to Dirtme's break. Plus, the fracture on mine had looked pristine.

I'd made two in-deep placements into that flared pod that day, at slightly different locations in the back of that pod, one of them up against the inner right side. I believe the fracture occurred at one of those placements, and that it might've been the same or very nearly the same as that of Dirtme's, judging from the fracture.

The low load it took to fracture a steel component on the cam makes the flare-induced force amplification a possible factor in this second incident. OP is investigating this carefully and thoroughly. For now, I'm okay with letting them do just that.

The fracture resembled that of Dirtme's cam very much. His occurred on a short lead fall. Mine happened as a result of only downward pulls by hand. The force of the pulls were about that of setting a piece hard, but not as hard as all out funking.

Perhaps the notion of breaking one by hand isnt so unrealistic.

In any case, the fact that you were able to cause that type of material failure by simply yanking on the cam is (IMO) surprising and important. I hope that Omega is willing to make the results of their testings available to the public.

On a side note, I exchanged a few emails with Black Diamond concerning the phenomenon of force amplification in flaring placements and resulting material failures but they were unwilling to share any information.

BD wrote:

Thanks for your email and for your support over the years. > > We have tested cams in real rock in all kinds of placements using > sandstone, quartzite limestone and granite. Repeatability is the key for > good lab testing during the development of any product. We really put > these units through the ringer using static tensile tests, our dynamic > drop tower and a plethora of other highly classified super technical top > secret developmental testing scenarios. For your information, camming > devices are tested using file plates when certified. Not exactly > realistic when it comes to real world use, but again, is reasonable and > is utilized for consistency purposes at the notified laboratories that > certify climbing gear. Testing information is not available to the > general public nor published in any format for public use. > > Best Regards, > Jeff Maudlin > BDEL

BD wrote:

Bryan,

We do all kinds of testing, in all kinds of scenarios. Some official, some unofficial. We don't have detailed or quantitative enough answers to these questions to share. We don't release testing data other than what is required for us to certify these. Everything else is internal, proprietary, and not available to the outside at this time. My apologies and we do appreciate your understanding and support.

Best, Jeff

Pretty standard reply I guess. I had hoped they had some published data to share but wasnt really surprised that they did not.

The LC (three sets of lobes shown independently) has its smaller (extended) lobes traveling much further relatively, and in a direction more perpendicular to the plane of the lobe. I can see how if you have this stuffed into a flaring pocket you could really generate some weird torques.

Sorry that the scales are different in the pictures and the LC doesn't look like a real LC.

That's interesting--and could potentially shed some light into the particular failure mechanism for this cam. Does anyone know if this is how the link cams work? I had always thought that only one set of the retractable cams were in contact with the rock for any given placement--as opposed to all three.

The LC (three sets of lobes shown independently) has its smaller (extended) lobes traveling much further relatively, and in a direction more perpendicular to the plane of the lobe. I can see how if you have this stuffed into a flaring pocket you could really generate some weird torques.

Sorry that the scales are different in the pictures and the LC doesn't look like a real LC.

That's interesting--and could potentially shed some light into the particular failure mechanism for this cam. Does anyone know if this is how the link cams work? I had always thought that only one set of the retractable cams were in contact with the rock for any given placement--as opposed to all three.

Curt

I think the basics of the diagram are correct, but it's back to front at present. In most cases, it'll be the front (ie. smallest) lobes that will remain relatively stationary (since they're the ones actually camming against the rock), and the large ones (loose, when the small cams are engaged) making the biggest movement.

... Actually, just point the stems in the diagram in the opposite direction. This would be much closer to how the link cams work (smallest at the axle, largest extended along the stem).

The LC (three sets of lobes shown independently) has its smaller (extended) lobes traveling much further relatively, and in a direction more perpendicular to the plane of the lobe. I can see how if you have this stuffed into a flaring pocket you could really generate some weird torques.

Sorry that the scales are different in the pictures and the LC doesn't look like a real LC.

That's interesting--and could potentially shed some light into the particular failure mechanism for this cam. Does anyone know if this is how the link cams work? I had always thought that only one set of the retractable cams were in contact with the rock for any given placement--as opposed to all three.

Curt

I think the basics of the diagram are correct, but it's back to front at present. In most cases, it'll be the front (ie. smallest) lobes that will remain relatively stationary (since they're the ones actually camming against the rock), and the large ones (loose, when the small cams are engaged) making the biggest movement.

... Actually, just point the stems in the diagram in the opposite direction. This would be much closer to how the link cams work (smallest at the axle, largest extended along the stem).

Agreed, the contact of the loose cams is incidental, and it would probably be caused mostly by irregularities in the surface.

Good read all. I usually avoid the "injuries and accidents" forum, but this thread was worth reading over the last couple of days.